Found an infinite loop w/out Workout Draw: Start with the Zen deck, cut workout cards every time you can, get Pre-Workout Mix, and you can stack just enough cards on the third competition to gain an infinite loop assuming good RNG. I ended up in the Iron Invitational with Twerk and Back cut from my deck and Pre-Workout Mix added, resulting in a deck that can loop infinitely.
If you can't find Pre-Workout Mix, Vitamin B+ will work similarly, just with less potency.
Thanks @The Gemfish for the idea!